Pulsus paradoxus in asthma.

Ninety-three patients with asthma were examined on 308 occasions for systolic fluctuation of blood-pressure during quiet breathing. Pulsus paradoxus (fluctuation of 10 mm Hg or greater) was present on 110 occasions. A pulses paradoxus was associated with greater airflow obstruction (average peak expiratory flow-rate 33.6% of the predicted) than an absent pulsus paradoxus which was associated with a peak expiratory flow-rate of 55.4%. However, pulsus paradoxus was often present in mild obstruction and absent in severe obstruction. In six patients the effect of changing respiratory pattern on systolic fluctuation was studied. Systolic fluctuation was directly related to the inspiratory flow-rate. This is probably one of the major reasons why association of airflow obstruction with pulsus paradoxus is not constant.